What is access control?
Access control is managing who may enter a site and recording that they did — by officer, by system, or by both. It is the core duty on most manned sites.
The record is what makes it useful after the fact. Knowing who was on site at a given time answers questions about theft, about safety in an evacuation, and about contractor activity.
Officer-operated access control depends on assignment instructions being specific about who is permitted, because an officer deciding in the moment will be persuaded eventually.
Tailgating is the failure mode no system prevents, which is why access control is usually a combination of a system and a person rather than either alone.
In practice
A turnstile at a corporate headquarters, morning peak.
Three hundred people badge through in twenty minutes. Two walk in behind somebody who holds the gate open, because that is what polite people do and the officer is dealing with a delivery.
The system is working perfectly. The control it provides has been defeated by ordinary courtesy, which is the way it is defeated almost every time.
Access control is a social arrangement with hardware attached, and designing it as though it were only hardware is how a building with excellent turnstiles has no idea who is in it.
What goes wrong in practice
- Visitor records kept but never usable — illegible, unsearchable or not retained.
- Instructions that do not say who may be admitted, leaving each case to judgement.
- Contractor access granted without recording what they were there to do.